1. Technical Field
The present invention relates to an improvement of a hard disk device employed, for example, for sorting data magnetically in computers.
2. Description of the Prior Art
A hard disk drive device includes a magnetic disk or disks for storing magnetic data. Such disks are mounted on a hub, i.e., the rotational member of a motor. In order to write the desired magnetic data into a sector on the magnetic disk or to read the data therefrom, the disk or disks are rotated at high speed by moans of the motor.
In recent years, it is desired to provide a smaller, thinner, and lighter weight, as well as impact resistant magnetic storage means, especially a hard disk drive device.
When impact is applied to the hard disk means, the impact energy is apt to be concentrated in the bearing means journalling the rotor or hub of the motor for driving the magnetic disk, so that the bearing means is the element that is most liable to be damaged.
When the bearing means is damaged, the accuracy of rotation of the magnetic disk will diminish, the reading and writing of the magnetic data can not be accomplished accurately, and noise and vibration are produced.
One of the countermeasures which can be taken for preventing the damage to the bearing means is to strengthen the bearing means itself. This countermeasure is confronted with the problem that the magnetic disk is fabricated under a predetermined standard to have an outer diameter of 2.5 inches or 3.5 inches, and the central aperture thereof is also restricted by such a standard to have an inner diameter of 20.0 mm or 25.0 mm respectively. In other words, the outer diameter of the hub as well as that of the magnet and/or the stator are also adapted to be defined under the standard in accordance with the diameter of the central aperture of the magnetic disk, so that a bearing means of sufficient size and strength can not be used.
It is not necessary to make the diameter of the central aperture of the magnetic disk as mentioned above. However, a magnetic disk having a central aperture of a diameter larger than that defined under the predetermined standard and a hard disk drive means including a motor larger in the outer diameter of its hub for driving such disk have not been realized. This is because the enlargement of the diameter of the central aperture of the magnetic disk leads to a reduction of the surface area of the magnetic disk and of the capacity of the memory for storing magnetic data.
Although the countermeasure that reducing the radial thickness of said magnet and/or the radial length of the stator to provide a space required for enlarging the bearing means can be taken, this will have an adverse impact on the function of the motor such as the rotational torque or the rotational speed. In this connection, this countermeasure can not be adopted.
Accordingly, the object of the present invention is to provide a hard disk drive device having a bearing means of larger size and sufficient strength, improved impact resistance, high accuracy of rotation, and high reliability.
These and other objects are achieved by a hard disk drive device comprising a motor including a rotor or hub and a stator, and a magnetic disk. The hub has a flange depending downwardly from the outer periphery thereof. The hub is journalled rotatablly on a base by means of a bearing means. The hub is provided with a magnet on the inner peripheral surface of the downwardly depending flange. The stator is provided on the base so as to opposed face to face with said magnet. The stator includes coils The magnetic disk or disks having a central apparatus to be fitted around the outer peripheral surface of the flange provided around the hub of the motor. The magnetic disk is adapted to be rotated by means of said motor. The inner diameter of the downwardly depending flange of said hub of the motor is enlarged, so that the outer and inner diameters of the magnet confined within the downwardly depending flange, and the outer and inner diameters of the stator are also enlarged to allow the outer diameter of the bearing means to be enlarged.